In communication systems such as a digital TV broadcast system or a wireless local area network (WLAN) system, interference signals usually appear in signals received by a receiver. The interference signals worsen the signal-to-noise-ratio (SNR) of the received signal at frequencies where the interference signals appear, which severely affects the performance of the receiver. In order to mitigate the negative effect of the interference signals, it is required for the receivers of these systems to have strong anti-interference capability.
A notch filter is generally used in the receivers to combat interference. However, since the bandwidth of the notch filter is preset but the bandwidth of the interference signal is generally unknown, this method cannot remove the interference signal completely. Another method for combating interference is to detect interference for each subcarrier by converting the received signal into a frequency domain using discrete Fourier transform (DFT) or fast Fourier transform (FFT), and notch the subcarrier on which interference is detected. However, there still are some problems for this method. In one hand, false accept rate of this method is high since it is hard to determine the interference detection threshold. In another hand, when a subcarrier is encountered with an interference signal, both the desired signal and the interference signal would be filtered out simultaneously, which adversely affects the desired signal.
With the wide spread of multi-carrier systems in areas of broadcasting and communication, it is required to provide a method for detecting and mitigating interference in a multi-carrier receiver.